The plurality of contract parties under Iranian law and principles of European contrary law

In lranian civil law,in discussing convection some rules has been legistated on intractors and convinced that each part of contract is only one person.Although ,in many contract each party is more than one person.In this research commitment,law,duties and responsibility of each party is studied.The obligations and assignment pf a cotract must be specified,otherwise,the rules and the principles should be find for it.To compensate for losses offending of the implementation of the commitment,responsibility,contract each of tge parties.  for this cases in Eurupean contracts principles is assigned surety responsibility.But in Iran the principles is based on equality that is not defended and the rights that belong to each of the parties should be discussed.